The president of the Australian Human Rights Commission has launched another attack on the Government's asylum seeker strategy, questioning the legality of key parts of the policy.

At a Senate estimates hearing in Canberra, Professor Gillian Triggs described the so-called "no advantage" policy as having no legal content and no comparison in international law.

She has also questioned whether the information given to asylum seekers about their legal rights when they first arrive is adequate under Australia's international obligations.

The Human Rights Commission has long expressed its frustration at aspects of the Government's asylum seeker policy.

"We urge the Government to reconsider its offshore processing as a policy," she said.

"We urge the Government to embark on assessing the validity or otherwise of the claims to refugee status."

In recent days Greens Senator Sarah Hanson-Young has been questioning officials from the Immigration Department about the Government's new enhanced screening process for asylum seekers arriving by boat.

Late last night the department tabled the preamble read to people before their screening interview - it does not say they are entitled to ask for legal advice.

Professor Triggs questioned whether the Immigration Department is complying with its legal obligations to asylum seekers.

"The positive obligation is to provide reasonable facilities under the Migration Act to those who have arrived unlawfully in Australia... [to] be able to make a claim for asylum and to have reasonable access to legal advice," she said.

"Now, I say that knowing that I believe that the Commonwealth position at the moment is to the contrary.

"I think that the department is bound both as a matter of our own domestic law under the migration law and as a matter of international law - which is obviously my brief - to advise people that they have a right to seek legal advice."

Decision to deny commissioner detention centre inspection 'curious'

Immigration officials told the hearing that if someone asks for legal advice, they are provided with access to a phone, a phonebook and an interpreter.

Professor Triggs has questioned whether the United Nations Human Rights Committee would see that as appropriate under Australia's international obligations.

"I think I could say that probably, and I don't know, but probably, the committee would find that not adequate," she said.

"So it's the sort of matter that needs to be tested.

"So the questions you've raise quite usefully are ones that one can give a hypothetical answer to, but where we haven't yet had them determined by our courts. And that is one of the difficulties of isolating these unlawful maritime arrivals from access to proper advice."

The Human Rights Commission president says she accepts that she does not have jurisdiction over the offshore processing centres on Nauru and Manus Island.

But she says the commission is still in discussions with the head of the Immigration Department, Martin Bowles, about whether she can be invited to inspect the centres.

It's very unclear what you're comparing it with. No advantage over what?

Professor Gillian Triggs

"He said that he would give the matter some consideration, because I have suggested to him that I completely understand the legal limits on my mandate," she said.

"But that I think as the national human rights institution in a matter of enormous importance to the country, and indeed to our international reputation, it would make a certain degree of sense were I to be invited, with the facilitation of the Australian Government, to go to both of those places.

"As you well know, many people have visited. It seems rather curious that the commission has not been able to do so."

Professor Triggs also confirmed the commission is receiving communications from both centres.

"I'm also seeking further legal advice as to exactly what our powers would be, were we to take a matter as a formal complaint," she said.

"So that matter remains to be resolved and I very much hope that we will have a resolution of that question in the next two or three weeks."

'No clarity' on no advantage policy

The Senate estimates committee heard on Monday that the department has recently finalised advice to the minister on how to apply its no advantage principle to the 19,000 people who have arrived by boat since August last year.

Not one person has been able to lodge an asylum claim.

Professor Triggs says the no advantage principle appears to not have legal content.

"It's very unclear what you're comparing it with. No advantage over what?" she said.

"So is it, like the people I've been to see in Oman, in Jordan, who have been in refugee resettlement camps for generations? Is it five or 10 years in Malaysia or Indonesia? There's no clarity as to exactly what that means."

She says the commission is continuing to urge the Government to allow people released into the community on bridging visas to work, as most of them end up having their refugee claims accepted.